1. Field of the Invention
The present invention relates to a lens driving unit and to an image photographing module having the lens driving unit. More particularly, the present invention relates to a lens driving unit including a curved vibration piezoelectric motor which is thin, has a small volume, and can perform a zooming function or an auto-focusing function in a digital camera, and to an image photographing module having the lens driving unit.
2. Description of the Related Art
In recent times, the utilization of camera modules having an auto focusing (AF) function or a zooming function in mobile electronic devices such as mobile phones has increased. Camera modules used in mobile phones should be very small and thin to allow size reduction of the mobile phones.
To perform a zooming or auto-focusing function, a lens barrel supporting a lens needs to be moved along a guide unit. Examples of driving devices in this regard are a stepping motor, a piezoelectric motor, and a ultrasonic motor. For example, a stepping motor is powered by DC and changes a continuous input pulse into a stepwise waveform. Such an arrangement has fast response characteristics when the steps are small.
However, due to the size of a deceleration gear, connection portions, and the motor itself in such arrangements, the size of a driving module is large. Also, as the number of components increase, the manufacturing cost of the camera module increases. Thus, in order to manufacture light and compact products, a ultrasonic motor or a piezoelectric motor is frequently used in a camera module for compact digital cameras or mobile phones.
In addition, a ultrasonic motor has high torque at a low driving speed, and can be manufactured in a variety of structures as compared to conventional motors.
However, in the case of a conventional lens driving unit actuated by an inertial piezoelectric motor, a piezoelectric unit needs to be disposed at a side portion of a lens module or a shutter module. As a result, the volume or width of the side portion of the camera module is increased.
Also, in the case of a conventional lens driving unit actuated by a curved vibration piezoelectric motor, a shutter module having a shutter and an aperture cannot be installed at a height almost matching an optical axis direction of a lens module due to the volume of the piezoelectric motor driving unit that is disposed in the lens module. Instead, the shutter module must be installed above the lens module in the optical axis direction. As a result, the thickness or height (length in the direction of the optical axis) of the camera module is undesirably increased.